Pre ordering Series X with gift cards

Just to add. expiration for gift cards (money) is 90 days.

This is what i want to know, i preorder an Xbox series X when it becomes available with say a 90 day microsoft rewards $100 gift card. If the preorder is longer then 90 days out, do i lose that $100 or is it redeemed at the time of preorder. I will be
using a credit card for the rest of the order.

This page covers most of those details. Check the FAQ at the bottom.

The important parts would be

"Do gift cards expire?

No, gift cards purchased at retail never expire. Note that promotional gift cards like those from Microsoft Rewards or Xbox Live Rewards do expire."

"What is the difference between a Microsoft Gift Card and an Xbox Gift Card?

The cards work just the same. Once redeemed to your Microsoft account, you can spend your balance at Microsoft Store online, on Windows, and on Xbox."

"Where can I spend a gift card?

Once redeemed to your Microsoft account, your gift card balance is available to spend when you shop at Microsoft Store online, on Windows, and on Xbox. Gift cards do not currently work at physical Microsoft Stores."

Should cover you. One thing I'm not certain with is if "gift cards" can be used to pre-order physical goods. Might want to check with Microsoft Store support on that?

Hi, yeah I bought a Microsoft gift card from the Microsoft store and redeemed it straight away. I saw there's some good deals on Xbox gift cards through amazon, and was wondering what if I bought them and redeemed them as soon as they arrive.

Can they expire after being redeemed?

There is no difference between the two, though I would say that with caution, depending on where you got them from? And please note that some of them do have expiration, so review the fine print before hoarding the points. My gut says this would be gift
cards from Microsoft Rewards? If so, definitely check the expiration on those. I lean towards that guess on redeeming the "Hot Deals" for gift cards? If that is the case, then definitively there is no difference between the two there.

If you have more specific questions, or if this doesn't cover what you're looking for, please let me know!